Trimerization of butadiene

ABSTRACT

THIS INVENTION RELATES TO AN IMPROVED PROCESS FOR THE TRIMERIZATION OF BUTADIENE TO CYCLODODECATRIENE-(1,5,9) USING A CATALYST COMPRISING AN ORGANOLUMINUM SESQUICHLORIDE AND A TITANIUM COMPOUND WHEREIN INCREASED YIELD OF THE DESIRED PRODUCT AND IMPROVED OPERABILITY OF THE PROCESS ARE REALIZED BY RECYCLING INTO THE REACTION ZONE AT LEAST A PORTION OF THE BY-PRODUCT 1,5-CYCLOOCTADIENE AND 4-VINYLCYCLOHEXENE FROM THE TRIMEIZATION REACTION.

Patented Apr. 11, 1972 3,655,795 TRIMERIZA'HON F BUTADIENE David Lee Sullivan, Victoria, Tex., assiguor to E. L du Pont de Nemours and Company, Wilmington, Del. No Drawing. Filed Jan. 11, 1971, Ser. No. 105,647

Int. Cl. C07c 3/18 US. Cl. 260-666 B 7 Claims ABSTRACT OF THE DISCLOSURE This invention relates to an improved process for the trimerization of butadiene to cyclododecatriene-(1,5,9) using a catalyst comprising an organoaluminum sesquichloride and a titanium compound wherein increased yield of the desired product and improved operability of the process are realized by recycling into the reaction zone at least a portion of the by-product 1,5-cyclooctadiene and 4-vinylcyclohexene from the trimerization reaction.

BACKGROUND OF THE INVEN'I'ION The production of cyclododecatriene-(1,5,9) by subjecting butadiene to the action of various catalysts is known. Butadiene trimerization catalysts, based on alkylaluminum chlorides and titanium halides, such as those described in Schneider et al., US. Pat. No. 3,076,045, and Wilke US. Pat. No. 2,964,574, Koch et al. US. Pat. No. 3,381,045, Eleuterio et al. US. Pat. No. 3,381,047, and Brenner U.S. Pat. No. 3,344,199 are known. The use of solvents in the trimerization of butadiene is described in US. Pat. No. 3,420,899, in British Pat. No. 1,061,027 and in Canadian Pat. No. 810,719. In British Pat. No. 1,061,027 a decreased ability of the catalyst to form the desired cyclododecatriene is ascribed to build-up in concentration of by-product vinylcyclohexene in the recycled solvent. The back mixing of a part of the reaction product into the reaction mixture in the oligomerization of butadiene over a nickel complex catalyst is described in US. Pat. No. 3,272,876.

SUMMARY OF THE INVENTION The present invention is an improvement over the above-mentioned processes in yield of 1,5,9-cyclododecatriene from butadiene and in operability of the process. The improvement comprises recycling into the reaction zone from 5 to 25 weight percent based on 1,5,9-cyclododecatriene of the by-products 1,5-cyclooctadiene and 4-vinylcyclohexene formed in the trimerization reaction. Since these by-products are normallyremoved in a subsequent refining step, their inclusion in the trimerization stream does not introduce a material which requires an additional step for removal after the reaction is completed. The catalyst system for the trimerization is prepared from certain hereinafter defined aluminum sesquichlorides and titanium compounds together with a promoter for the catalyst system selected from the group consisting of water, oxygenated organic compounds and either oxygen or oxygen containing gases or liquids. For convenience, the exact composition of the organometallic compound may be varied and described as any composition having the following ratio of composition:

wherein Z is selected from the class consisting of alkyl radicals containing from 2 to 4 carbon atoms and the phenyl radical. The molar ratio of the aluminum sesquichloride to promoter should be maintained at from l/ .05 to 1/1 when anhydrous buta'diene is used as the starting material with from 1/0.2 to 1/0.'6 being the especially preferred range.

As indicated above, the promoter for the catalyst system may be water, oxygenated compounds, oxygen or oxygen containing gases or liquids. The amount of water when used as a promoter is in the range of 0.3 to 0.9 mole per mole of aluminum compound. The amount of oxygen as oxygen gas or in an oxygen containing gas such as air is in the range of 0.1 to 0.7 mole per mole of aluminum compound. The amount of oxygen con taining compound used is in the range of 0.05 to 1.0 mole per mole of the aluminum compound.

The oxygen containing compounds comprise aldehydes, ketones, epoxides, and anhydrides. The aldehydes suitable for use as a promoter have the structure RCHO' where R is hydrogen or a hydrocarbon radical containing from 1 to 15 carbon atoms as stated in claim 1. The ketones suitable for use as promoters have the structure Rte (to where R is a phenyl or an alkyl radical of from 1 to 10 carbon atoms and R is a phenyl or an alkyl radical of from 1 to 10 carbon atoms, and where R is an alkylene radical of from 4 to 15 carbon atoms. Diketones having the formula i R4CCH2 R5 are also useful promoters. R is an alkyl radical of from 1 to 10 carbon atoms and R is an alkyl radical of from 1 to 10 carbon atoms. The epoxides suitable for use have the structure wherein R is a hydrocarbon radical of from 1 to 10 carbon atoms and R is a hydrocarbon radical of from 1 to 10 carbon atoms, and wherein R is an alkylene radical containing from 6 to 20 carbon atoms. The anhydrides suitable for use in the present invention have the structure 0 Bfl-C-O- R wherein R is an alkyl radical of from 1 to 10 carbon atoms, and R is an alkyl radical of from 1 to 10 carbon atoms.

If the recycled by-products contain oxygen or oxygenated organics, it is necessary to adjust the amount of promoter that is added with the catalyst to limit the total aluminum sesquichloride/promoter ratio to the prescribed ratio. Additionally, it is advantageous to remove peroxides present in the recycled by-products by eluting these by-products through activated alumina before their addition to the reactor. If the by-products are stored under nitrogen, it is not necessary to treat them with activated alumina. It is advisable, however, to determine the amount of water in these by-products as well as the presence of peroxide to assure trimerization equal to or below the aluminum sesquichloride/promoter ratio prescribed. The presence of oxygenated organic compounds can be determined from the infrared spectrum of the byproducts. If oxygenated organics are present, it is again necessary to adjust the amount of promoter added together with the catalyst.

Although the by-products recycled to the trimerization reactor are predominantly 1,5-cyclooctadiene (COD) and 4-vinylcyclohexene (VCH), it is possible that other byproducts are present also. Since the cyclododecatriene (CDDT) is separated from combined VCH/ COD by distillation, other by-products with volatilities similar to VCH/ COD may also be present.

In the catalytic trimerization of butadiene, the ratio of aluminum sesquichloride to titanium is not so critical.

4 stirrer and internal cooling coils through which water .s circulated to control the temperature of the reaction medium. Temperature is monitored by a thermocouple connected to a transformer which activates a solenoid valve The molar ratio of the aluminum sesquichloride to titani- 5 controlling the cooling water flow through the coils. The urn compound may be varied from 3/ 1 to 30/1 with ratios temperature is held at 75 C.:1 C. Oif gas from the reof from 5/1 to 15/1 being preferred. Higher ratios may actor is passed through a condenser, then to a mercury be used but are not desirable because of the expense of seal which is used to regulate pressure. In each of the the aluminum sesquichloride. examples the reactor is charged with CDDT and the tem- Generally speaking, any tetravalent titanium compound perature is raised to 75 C. while simultaneously injecting is operable in the present process as long as it is soluble ca. 0.002 mole TiCl and 0.03 mole aluminum sesquichloin the reaction medium to an extent of at least 0.01 mole ride. The CDDT is sparged with butadiene as the catalysts percent as based on CDDT at 20 C. and which does not are added. After the reaction starts, as evidenced by butacontain a substituent that inactivates the aluminum sesdiene consumption, the catalyst ratios are adjusted and quichloride catalyst. These compounds generally have the water is incrementally increased until all three catalyst formula T iA, wherein A is selected from the class concomponents are added in the molar ratios shown in the taining Cl, Br, I and OR, wherein R is a hydrocarbon radexamples. The addition of combined 4-vinylcyclohexene ical of from 1 to carbon atoms. The four As used in and 1,5-cyclooctadiene (VCH and COD) or either coma given titanium compound may be the same or different. pound is then started and rapidly increased until the The catalyst may be prepared by reacting the promoter 20 amount indicated in the examples is being continually with the aluminum sesquichloride followed by reaction of added to the reactor. The crude CDDT obtained during the product so formed with the titanium compounds. Howsteady state operation overflows through the side arm and ever, for continuous operation, it is convenient to add all fills a second 1500 ml. reactor. Additional butadiene is three catalyst components separately and simultaneously consumed in this second stirred reactor as this gas is to the reaction vessel. If desired, all of the catalyst may sparged into the crude product collected from the first be added as gases in separate butadiene streams as by vareactor. Product obtained from the second reactor is colporizing either the titanium compounds or the aluminum lected continuously and the catalyst in the crude reaction compound and adding the vapor to separate butadiene product is deactivated by saturation with anhydrous NH streams. The average rate of reaction throughout a run is ex- The present process is also applicable to the trimerizapressed as the number of grams/liter of reactor space/ tion of substituted butadienes such as isoprene. hour (g./l./hr.) of crude product of the analysis shown The butadiene trimerization reaction temperature genthat were actually obtained. The amount of by-product erally is maintained at from 20 C. to 120 C. and prefadded is not included in this number so that productivity erably at from about 60 C. to about 90 C. At lower is expressed on a net basis. In all cases the yield to CDDT temperatures, the reaction rates become unduly slow and 3 is about 23% higher when VCH/ COD is injected as comat higher temperatures increasing yield losses to by-prodpared with steady state yield obtained without by-product ucts occur. addition. In Example V for instance, the average yield Pressure in the instant invention can be varied from of CDT without by-product addition is 86.5% while the /2 atm. to 50 atm. preferably at from 1 to 5 atm. average yield of CDDT is 89.1% when combined by- When carried out in a continuous manner, the reaction 40 products are added. This is seen in the examples where can be made to occur in multiple stages to take advanaddition of 6-16 wt. percent by-products, based on steadytage of residual catalyst activity and the recycled bystate productivity of crude CDDT, resulted in an average product can be fed at any desired stage. CDDT yield of 89.1%. The addition of COD only results Cyclododecatriene is a valuable chemical intermediate in nearly a 2% net ODDT yield increase which is slightly which can be readily oxidized to succinic acid which is less than the 2.6% net yield increase obtained with inuseful in the production of plastics such as polyamides. jection of combined VCH/COD. Best results on yield im- It also may be hydrogenated in known manner. Thus, provement of CDDT and in general operability of the cyclododecene or cyclododecane is obtained from cycloprocess are realized when the amount of by-product added dodecatriene. These hydrogenated products may, in turn, is in the range of about 10 to about 20 percent, based on CDDT produced.

TABLE I.SYNTHESIS 0F CDDT FROM BUTADIENE IN THE PRESENCE OF RECYCLED VCH AND/OR COD Example I II III IV V Molar catalyst ratio ((C2H5)3 AlzCh/TiChIHzO) 10/1/5 11/ 1/5 10/1/4 10/1/4 10/1/4 Steady state productivity (g. crude CDDT/l. reactor space/hr.) 970 890 780 670 875 'liCh concentration (g./ml. cyclohexane) 0.0286 0. 0546 0.0565 0. 0555 0. 0462 Catalyst feed rate (g./l./hr.) .0 1.0 1. 0 l. 0 1.0 By-product(s) fed to reactor 4 VCH/COD 3 VCH/COD 3 VCH/COD None I (28/72) (35/65) (35/65) Amount of by-produet fed (wt. percent based on steady productivity of crude CDDT) 7.3 6.8 13 16 Percent distribution in crude: 1

CDDT 88. 4 88.6 89.7 89.1 86, 5o VCH and COD... 4. 20 4. 90 1.30 1.80 7.56 Non-volatile residue 6. 50 9.00 9. l 5. 94

1 Temperature, 75 (1.. pressure 1.5 p.s.i.g.

2 Results obtained by subtracting amounts of VCH and/0r COD injected from amounts present in the crude product to yield net dimer production.

be oxidized in known manner to form the corresponding dicarboxylic acids.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 3 Not treated with activated alumina. 4 Treated with activated alumina.

I claim:

1. In a continuous process for the production of 1,5,9-cyclododecatriene which comprises contacting butadiene in a reactor with a catalyst system formed by mixing an aluminum compound of the structure wherein Z is selected from the class consisting of alkyl radicals containing from 2 to 4 carbon atoms and the phenyl radical; a titanium compound at the formula.

TiA, wherein A is selected from the class consisting of Cl, Br, I and OR wherein R is an organic radical of from 1 to 20 carbon atoms, in an amount such that the molar ratio of the aluminum compound to the titanium compound is maintained at from 3/1 to 30/1; and a promoter for the catalyst system wherein the promoter is selected from the group consisting of water in an amount of 0.3 to 0.9 mole per mole of aluminum compound, oxygen in an amount of 0.1 to 0.7 mole per mole of aluminum compound and oxygen containing compounds in an amount of 0.05 to 1.0 mole per mole of aluminum compound, wherein the oxygen containing compound is of the class consisting of compounds of the structures RCHO,

wherein R is hydrogen or an alkyl radical of from 1 to 15 carbon atoms, R is a phenyl radical or an alkyl radical of from 1 to 10 carbon atoms, R is a phenyl radical or a hydrocarbon radical of from 1 to 10 carbon atoms, R is an alkylene radical of from 4 to 15 carbon atoms R is an alkyl radical of from 1 to 10 carbon atoms, R is an alkyl radical of from 1 to carbon atoms, R is an alkyl radical of from 1 to 10 carbon atoms, R is an alkyl radical of from 1 to 10 carbon atoms, R is an alkylene radical of from 6 to 10 carbon atoms, R is an alkyl radical of from 1 to 10 carbon atoms and R is an alkyl radical of from 1 to 10 carbon atoms; at a temperature in the range of 20 to 120 C. and at a pressure of 0.5 to atmospheres and recovering cyclododecatriene-l,5,9 along with by-products 1,5-cyclooctadiene and 4-vinylcyclohexcue; the improvement which comprises recycling into the reactor from 5 to 25 weight percent, based on the weight of 1,5,9-cyc1ododecatriene produced, of at least one of the by-products.

2. The process of claim 1 wherein the molar ratio of the aluminum compound to the titanium compound is from 5/1 to 15/1.

3. The process of claim 2 wherein the aluminum compound is ethylaluminum sesquichloride.

4. The process of claim 3 wherein the titanium compound is titanium tetrachloride.

5. The process of claim 2 wherein the by-product recycled to the reactor is 1,5-cyclooctadiene.

6. The process of claim 2 wherein the by-product recycled to the reactor comprises 1,5-cyclooctadiene and 4-vinylcyc1ohexene.

7. The process of claim 1 wherein the amount of byproduct recycled into the reactor is in the range of about 10 weight percent to about 20 weight percent, based on 1,5,9-cyclododecatriene produced.

References Cited UNITED STATES PATENTS 3,381,045 4/1968 Koch et al. 260666 B 3,381,047 4/1968 Eleuterio et al. 260-666 B 3,523,980 8/1970 Sullivan 260-666 B 3,272,876 9/1966 Levine 260-666 B DELBERT E. GANTZ, Primary Examiner V. OKEEFE, Assistant Examiner 

